I'm not sure that using a Security Assist rule to confirm the update is the best way to go about this. I think it might be easier to add in a message to the screen to inform the user of the update.
To start with in your update server behavior you need to make sure the update is going back to this same page but you should add in a url parameter to let you know that the page has been updated, like this:
redirect page: yourpage.php?updated=1
Once you have the redirect setup like this then you can add your message to the page that you would like the user to see only when the update occurs. Once you have added it to the page you can wrap a php if statement around it like this:
<?php if(issset($_GET['updated']) && $_GET['updated'] == 1){ ?>
your confirmation message goes here
<?php } ?>